The present invention relates to a crystalline titanosilicate catalyst having a structural (or framework type) code of MWW, which is usable as a catalyst in an oxidation reaction of the carbon-carbon double bond of a compound having a carbon-carbon double bond and at least one other functional group. The present invention also relates to a process for producing such a catalyst and a process for producing an oxidized compound using this catalyst.
More specifically, the present invention relates to a crystalline titanosilicate catalyst having a structural code of MWW, which is usable as a catalyst in an oxidation reaction of the carbon-carbon double bond of a compound having a carbon-carbon double bond and at least one other functional group using a peroxide as an oxidizing agent; a process for producing such a catalyst; and a process for producing an oxidized compound (particularly, an epoxy compound) comprising performing an oxidation reaction of the carbon-carbon double bond of a compound having a carbon-carbon double bond and at least one other functional group in the presence of the catalyst.
In general, xe2x80x9czeolitexe2x80x9d is a generic term for crystalline and porous aluminosilicates for, and the basic unit of the structure of a zeolite is (SiO4)4xe2x88x92 or (AlO4)5xe2x88x92 having a tetrahedral structure. However, it has recently been clarified that a structure peculiar to or analogous to such a zeolite is also present in many other oxides such as aluminophosphate.
In addition, according to the International Zeolite Association (hereinafter, simply referred to as xe2x80x9cIZAxe2x80x9d) who defines the zeolite in W. Meier, D. H. Meier, D. H. Olxon and Ch. Baerlocher, Atlas of Zeolite Structure Types, 4th Edition, Elsevier (1996) (hereinafter, simply referred to as xe2x80x9cAtlasxe2x80x9d), substances having the same structure, other than aluminosilicate, are described as an object substance in prescribing the structure, and these substances are called xe2x80x9czeolite-like materialsxe2x80x9d in the Atlas.
The history of this definition is described in detail in Yoshio Ono and Takeaki Yajima, Zeolite no Kagaku to Kogaku (Science and Engineering of Zeolites), pp. 1-2, published by Kodansha (Jul. 10, 2000).
In the present specification, the definition of xe2x80x9czeolitexe2x80x9d follows the above definition as described in Yoshio Ono and Takeaki Yajima, Zeolite no Kagaku to Kogaku (Science and Engineering of Zeolite), published by Kodansha (Jul. 10, 2000), where the term xe2x80x9czeolitexe2x80x9d may include not only aluminosilicates but also substances (such as titanosilicate) having a structure analogous to aluminosilicate.
In the present specification, the structures of zeolite and zeolite-like materials are denoted by a structural code, using three alphabetic capital letters, approved by IZA and originated in the standard substance which had first been used for the clarification of the structure thereof. The structural codes includes those contained in Atlas and those approved in the 4th edition, et seq.
In the present specification, the terms xe2x80x9caluminosilicatexe2x80x9d and xe2x80x9ctitanosilicatexe2x80x9d are not limited at all by the properties and/or states thereof (such as crystalline or amorphous, or porous or not porous). Therefore, in the present specification, these terms denote xe2x80x9caluminosilicatesxe2x80x9d and xe2x80x9ctitanosilicatesxe2x80x9d of all properties, unless specifically indicated otherwise.
In the present specification, the term xe2x80x9cmolecular sievexe2x80x9d means an activity or operation for classifying molecules by the size thereof, and the term also means a substance having such a function. zeolite is also included in the definition of a molecular sieve. The details thereon are described in the portion relating to xe2x80x9cmolecular sievexe2x80x9d in Hyojun Kagaku Yogo Jiten (Standard Chemical Glossary), edited by the Chemical Society of Japan, published by Maruzen (Mar. 30, 1991).
In recent years, various studies have been made on the oxidation reactions of organic compounds by using a titanosilicate which is a zeolite, as a catalyst, and using a peroxide as an oxidizing agent. Among these, a catalyst named xe2x80x9cTS-1xe2x80x9d, which is a crystalline titanosilicate, has been found to show an activity in an oxidation reaction using various peroxides, after the process for synthesizing the same was disclosed in U.S. Pat. No. 4,410,501, and TS-1 has been applied to various reactions. Specific examples thereof include the method disclosed in JP-B-4-5028 (xe2x80x9cJP-Bxe2x80x9d as used herein means an xe2x80x9cexamined Japanese Patent publicationxe2x80x9d), where TS-1 is used as a catalyst in the epoxidation of an olefin compound using hydrogen peroxide or an organic peroxide as an oxidizing agent.
The structural code of the titanosilicate TS-1 is xe2x80x9cMFIxe2x80x9d, which is the same code as the structural code of a representative synthetic zeolite ZSM-5, and TS-1 contains a ring structure containing ten (10) oxygen atoms (as described in Yoshio Ono and Takeaki Yajima, Zeolite no Kagaku to Kogaku, p. 4, published by Kodansha). As TS-1 has a relatively small pore size of 0.51 nm to 0.56 nm in terms of a calculated value therefor, the scope of olefin compounds which can be epoxidized by using TS-1 is limited. Further, both of the rate of the diffusion of an olefin compound as a reaction starting material into the inside of a pore and the rate of the effusion of an epoxy compound as a reaction product from the pore are low, so that a reaction activity which is sufficiently high, in view of the industrial use of TS-1, cannot be achieved in many cases. Furthermore, there is a problem such that a ring-opening reaction of the epoxy group of an epoxy compound as a reaction product is liable to occur, and the resultant selectivity is disadvantageously decreased.
On the other hand, JP-A-7-242649 (xe2x80x9cJP-Axe2x80x9d as used herein means xe2x80x9cunexamined Japanese Patent publicationxe2x80x9d) discloses a method of performing an epoxidation reaction of an olefin compound by using a crystalline titanium-containing molecular sieve having a structure similar to aluminum-free zeolite Beta (structural code: *BEA) as a catalyst and by using hydrogen peroxide or an organic peroxide as an oxidizing agent.
Since the *BEA has a large pore diameter as compared with that of the structural code of MFI for the titanosilicate TS-1, an effect of enabling a reaction of a sterically bulky compound or an effect of elevating the diffusion rate to thereby improve the resultant reaction rate was expected. In some examples of the above-mentioned Patent publication, a compound which does not react even in the case using the titanosilicate TS-1 can be actually oxidized. However, there are caused problems that the conversion of an oxidizing agent is low when hydrogen peroxide is used as the oxidizing agent for the epoxidation reaction, and that a ring-opening reaction of the epoxide is caused to produce a corresponding glycol, and as a result, the resultant selectivity is decreased. Further, in the case of the molecular sieve as described in this Patent publication, the decreasing rate of activity is rather high. That is, the catalyst life is short, and therefore it is necessary to repeat the regeneration of the catalyst frequently, whereby this point seriously hinders the implementation of such a molecular sieve on an industrial scale.
On the other hand, in recent years, synthetic zeolites having a structural code of MWW, which is different from those of MFI or *BEA, are attracting attention. The process for producing the same is disclosed, for example, in JP-A-63-297210.
Further, according to Peng Wu, Takashi Tatsumi and Takayuki Komatsu, Chemistry Letters, 774 (2000), it has been reported that when a crystalline titanosilicate having the structural code of MWW and containing a titanium atom in the crystal structure thereof is produced, and cyclohexene is oxidized by using this crystalline titanosilicate as a catalyst and by using hydrogen peroxide, cyclohexene oxide can be produced.
However, the yield of the intended product is rather low, while both of the resultant epoxide and diol are produced in a considerably large amount, whereby a tendency of selectively providing any of these compounds is not observed. Therefore, there is a caused problem when this method is intended to be utilized industrially.
As described hereinabove, various proposals have been made for conducting the oxidation reaction of an olefin compound by using a titanosilicate as a catalyst and by using a peroxide as an oxidizing agent. However, industrially practicable techniques are rather limited, and further, in any of the above-mentioned cases, only an oxidation reaction of a simple compound having a carbon-carbon double bond is disclosed. There has not yet been reported a titanosilicate which is usable as a catalyst in the oxidation reaction of a compound not only having a carbon-carbon double bond and but also having at least one other functional group.
An object of the present invention is to provide a crystalline titanosilicate catalyst which is usable as a catalyst in a selective oxidation reaction of the carbon-carbon double bond of a compound having a carbon-carbon double bond and at least one other functional group.
Another object of the present invention is to provide a process for producing such a titanosilicate catalyst, and to provide a process for producing an oxidized compound by an oxidation reaction using the catalyst.
As a result of earnest study for solving the above-mentioned problems, the present inventors have found that a crystalline titanosilicate catalyst having a structural code of MWW can effectively function as a catalyst for a reaction wherein the carbon-carbon double bond of a compound having a carbon-carbon double bond and at least one other functional group is oxidized by using a peroxide, so as to provide an intended oxidized compound highly selectively. The present invention has been accomplished based on this discovery.
More specifically, the present invention, in an aspect, is a crystalline MWW-type titanosilicate catalyst, for producing an oxidized compound, which is usable in producing an oxidized compound by an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent. The catalyst has an MWW structure and is represented by the following (chemical) composition formula (1):
xTiO2.(1xe2x88x92x)SiO2xe2x80x83xe2x80x83Composition formula (1)
(wherein x is a number of 0.0001 to 0.2).
The present invention, in a second aspect, is a crystalline MWW-type titanosilicate catalyst for producing an oxidized compound, which is usable in producing an oxidized compound by an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent. The catalyst has an MWW structure and is represented by the following composition formula (2):
xTiO2.yM2O3.(1xe2x88x92xxe2x88x922y)SiO2xe2x80x83xe2x80x83Composition formula (2)
(wherein M represents at least one element selected from the group consisting of aluminum, boron, chromium, gallium and iron, x is a number of 0.0001 to 0.2 and y is a number of 0.0001 to 0.1).
The present invention in a third aspect is a process for producing the crystalline MWW-type titanosilicate catalyst for producing an oxidized compound according to the present invention in the above-mentioned first or second aspect thereof.
The present invention in a fourth aspect is a process for producing an oxidized compound, comprising: performing an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent in the presence of the crystalline MWW-type titanosilicate catalyst for producing an oxidized compound according to the present invention in the first or second aspect.
Best Mode for Carrying Out the Invention
Hereinbelow, the present invention will be described in detail with reference to the accompanying drawings as desired. In the following description, xe2x80x9c%xe2x80x9d and xe2x80x9cpart(s)xe2x80x9d representing a quantitative proportion or a ratio are based on mass, unless otherwise noted specifically.
At first, the present invention in the first aspect and the present invention in the second aspect will be described.
The present invention in the first aspect is a crystalline MWW-type titanosilicate catalyst for producing an oxidized compound, which is usable in producing an oxidized compound by an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent. The catalyst has an MWW structure and is represented by the following composition formula (1):
xTiO2.(1xe2x88x92x)SiO2xe2x80x83xe2x80x83Composition formula (1)
(wherein x is a number of 0.0001 to 0.2).
The present invention in a second aspect is a crystalline MWW-type titanosilicate catalyst for producing an oxidized compound, which is usable in producing an oxidized compound by an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent. The catalyst has an MWW structure and is represented by the following composition formula (2):
xTiO2.yM2O3.(1xe2x88x92xxe2x88x922y)SiO2xe2x80x83xe2x80x83Composition formula (2)
(wherein M represents at least one element selected from the group consisting of aluminum, boron, chromium, gallium and iron, x is a number of 0.0001 to 0.2 and y is a number of 0.0001 to 0.1).
In the crystalline MWW-type titanosilicate catalyst for producing an oxidized compound according to the present invention in the first aspect, the ratio of constituent units TiO2 and SiO2 present in the catalyst can be specified by the molar ratio therebetween. Therefore, xe2x80x9cxxe2x80x9d means the molar ratio of TiO2 present in the titanosilicate, and (1xe2x88x92x) means the molar ratio of SiO2 also present in the titanosilicate. In the other words, the ratio x/(1xe2x88x92x) merely shows the molar ratio of titanium/silicon, and this ratio does not exclude the presence of at least one other element in the above-mentioned crystalline MWW-type titanosilicate for producing an oxidized compound.
In the composition formula (1), the range of x is from 0.0001 to 0.2, preferably from 0.005 to 0.2, more preferably from 0.01 to 0.1. In addition to the titanium species which have been introduced into the framework by substituting with silicon, a titanium species may be present at a site outside the crystal framework (or skeleton). For example, a 6-coordination titanium species or an anatase-like titanium oxide may be present together with the above-mentioned titanium species. However, such a titanium species outside the framework generally has a tendency-such that it promotes a side reaction or narrows the pores in the titanosilicate so as to inhibit the diffusion of a substance relating to the reaction. Therefore, the titanium species present at a site outside the crystal framework, if present, may preferably be present in a smaller amount.
In general, the x specified in the composition formula (1) shows an estimated ratio of titanium contained within the framework. In practice, when titanium is present outside the framework in addition to titanium within the framework, it is difficult to precisely quantitate the titanium contained within the framework. In general, for example, in the ultraviolet-visible absorption spectrum of a titanosilicate, the absorption in the vicinity of 210 nm is assigned to titanium within the framework, the absorption in the vicinity of 260 nm is assigned to a 6-coordination titanium species outside the framework, and the absorption in the vicinity of 330 nm is assigned to an anatase-like titanium species. Therefore, if an absorption is present in the vicinity of 210 nm, this absorption reveals that the titanosilicate corresponding to the spectrum contains titanium within the framework. Actually, the titanosilicate catalyst according to the present invention in the first aspect has an absorption in the vicinity of 220 nm, and this absorption reveals the presence of titanium within the framework. However, when another absorption is present at other wavelengths, it is difficult to quantitatively discuss the ratio of these titanium species present in the titanosilicate, even in a case where other means such as nuclear magnetic resonance method or infrared absorption method is combined with the above ultraviolet-visible absorption spectrum.
Only one clear fact is that the value of the molar ratio of titanium to silicon calculated from the ratio between titanium and silicon determined by the component analysis such as elemental analysis, is the maximum value of the amount of titanium contained within the framework. As described above, it is difficult to directly determine the molar ratio of titanium contained within the framework. Therefore, in the present invention, the molar ratio of titanium to silicon calculated by the component analysis as x in the composition formula (1) is for convenience used as the molar ratio of titanium contained within the framework.
The crystalline titanosilicate catalyst according to the present invention in the first aspect having a structural code of MWW wherein silicon is partially substituted with titanium may contain an element other than titanium, silicon and oxygen, as long as such an element does not greatly cause an adverse effect on the reactivity of the catalyst. In a case where the catalyst according to the present invention in the first aspect is produced by a production process using boron as a structure supporting agent, as described hereinafter, a slight amount of boron may remain in the catalyst in many cases, even if an operation for removing boron is performed. However, boron in a small amount does not have any serious effect on the reactivity of the catalyst, and therefore, boron can be present in the catalyst in a substantial amount. In principle, other trivalent metals such as aluminum, gallium, iron and chromium may also be used as a structure supporting agent in place of boron, and in such a case, these elements may sometimes remain within and outside the framework.
In this case, there is formed a crystalline MWW-type titanosilicate catalyst for producing an oxidized compound according to the present invention in the second aspect. That is, the present invention in the second aspect is a crystalline MWW-type titanosilicate catalyst for producing an oxidized compound, which is usable in producing an oxidized compound by an oxidation reaction of a compound having a carbon-carbon double bond and at least one other functional group wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent. The catalyst has an MWW structure and is represented by the following composition formula (2):
xTiO2.yM2O3.(1xe2x88x92xxe2x88x922y)SiO2xe2x80x83xe2x80x83Composition formula (2)
(wherein M represents at least one element selected from the group consisting of aluminum, boron, chromium, gallium and iron, x is a number of 0.0001 to 0.2 and y is a number of 0.0001 to 0.1).
In the above composition formula (2), the number xe2x80x9cxxe2x80x9d has the same meaning as in the composition formula (1) and the number xe2x80x9cyxe2x80x9d is also a molar ratio of constituent unit M2O3 present in the catalyst. Similarly to the composition formula (1), the ratio of x/(1xe2x88x92xxe2x88x922y) represents merely a molar ratio of xe2x80x9ctitaniumxe2x80x9d/xe2x80x9csiliconxe2x80x9d and the ratio of y/(1xe2x88x92xxe2x88x922y) represents merely a ratio of xe2x80x9cat least one element in total selected from the group consisting of aluminum, boron, chromium, gallium and ironxe2x80x9d/xe2x80x9csiliconxe2x80x9d. Accordingly, these ratios do not exclude the presence of other elements in the catalyst according to the present invention in the second aspect. In the composition formula (2), y is a number of 0.0001 to 0.1, preferably 0.0001 to 0.05, more preferably 0.0001 to 0.03.
In the composition formula (2) according to the present invention in the second aspect, the number y can be determined from the component analysis values in a similar manner as in the case of the number x in the composition formula (1) according to the present invention in the first aspect. The form or state of the presence of M2O3 may be either within the framework or outside the framework. M is at least one element selected from the group consisting of aluminum, chromium, gallium and iron, and has a valence number of 3.
As used in the synthesis of MCM-22, an alkali metal such as sodium and potassium can be generally expected to function as a mineralizing agent, and therefore, the alkali metal may be used in the production of the catalyst according to the present invention in the first or second aspect for the purpose of accelerating the crystallization. However, in general, the alkali metal has a possibility of inhibiting the catalytic function of the crystalline titanosilicate, and therefore, it is preferred to remove the alkali metal from the crystalline titanosilicate by ion exchange or the like.
The MWW structure, which is one known structure of molecular sieves, is characterized in that it has a pore comprising a ring structure containing 10 oxygen atoms and has a super cage (0.7xc3x970.7xc3x971.8 nm). This structure has been approved by IZA after the publication of the above-mentioned Atlas. The details of the structure can be inspected, for example, on the homepage (http://www.iza-structure.org/) of the IZA Structure Commission (as of September, 2000). Examples of known molecular sieves having this structure may include MCM-22 (Science, Vol. 264, 1910 (1994)), SSZ-25 (European Patent No. No. 231860), ITQ-1 (Chem. Mater., Vol. 8, 2415 (1996) and J. Phys. Chem. B, Vol. 102, 44 (1998)), ERB-1 (European Patent No. No. 203032) and PSH-3 (U.S. Pat. No. 449409). The molecular sieve having structural code of MWW can be identified by the pattern of its characteristic X-ray diffraction (hereinafter, simply referred to as xe2x80x9cXRDxe2x80x9d). The XRD pattern may also be available as a simulation pattern of ITQ-1, for example, on the above-mentioned homepage. Representative examples of the diffraction line may include those shown in Table 1 below.
The present invention in the third aspect will be described below. The present invention in the third aspect is a process for producing a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound, comprising the following first and second steps:
First step
a step of heating a mixture comprising a template compound, a titanium-containing compound, a boron-containing compound, a silicon-containing compound and water, to thereby obtain a precursor;
Second step
a step of calcining the precursor obtained in the first step, to thereby obtain a crystalline titanosilicate.
The crystalline MWW-type titanosilicate catalyst for providing an oxidized compound according to the present invention can also be synthesized by a conventionally known direct synthesis method or a post-synthesis method such as an atom-planting method (with respect to the details of the atom-planting method, Yoshio Ono and Tastuaki Yashima xe2x80x9cScience and Engineering of zeolitesxe2x80x9d (Jul. 10, 2000), p 142, Kodansha; and Peng Wu, Takayuki Komatsu, Tatsuaki Yashima, Shin-ichi Nakata, and Hiroshi Shouji, xe2x80x9cModification of mordenite acidity by isomorphous substitution of trivalent cations in the framework sites using the atom-planting methodxe2x80x9d Microporous Materials 12 (1997) 25-37 may be referred to.). In the case of the atom-planting method, the catalyst may be synthesized, for example, by preparing a molecular sieve having a MWW structure containing boron or aluminum, removing at least a part of boron or aluminum through a water vapor treatment or the like, and then contacting the resultant residue with a titanium compound such as titanium trichloride.
A more efficient production process for the MWW-type titanosilicate catalyst may include a production process according to the present invention in the third aspect. That is, the process for producing a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound according to the present invention in the third aspect is a production process for a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound, characterized in that the production process comprises two steps, i.e., a step of heating a mixture comprising a template compound, a titanium-containing compound, a boron-containing compound, a silicon-containing compound and water, to thereby obtain a precursor; and a step of calcining the resultant precursor, to thereby obtain a crystalline MWW-type titanosilicate for producing an oxidized compound.
At first, the above first step is described below. The first step in the process for producing the crystalline titanosilicate of the present invention in the third aspect is a step of heating a mixture comprising a template compound, a titanium-containing compound, a boron-containing compound, a silicon-containing compound and water, to thereby obtain a precursor.
The xe2x80x9ctemplate compoundxe2x80x9d as used herein is a compound having a function of, in the synthesis of zeolite having an MWW structure, determining the structure thereof and, particularly, of determining the shape of the pore. The template compound is not particularly limited, as long as it can be removed later by calcining. Examples thereof may generally include nitrogen-containing compounds. Specific examples of such a nitrogen-containing compound may include piperidine, hexamethyleneimine and/or a mixture thereof, but the template compound usable in the present invention is not limited to these specific compounds.
The titanium-containing compound which is usable in the first step is not particularly limited, as long as the titanium-containing compound can provide a gel-type product. Specific examples of the titanium-containing compound may include titanium oxide, titanium halide and tetraalkyl orthotitanates, but the titanium-containing compound usable in the present invention is not limited to these specific compounds. Among these, in view of easiness in the handling thereof, titanium halide and tetraalkyl orthotitanates are preferred. More specifically, titanium tetrafluoride, tetraethyl orthotitanate, tetrapropyl orthotitanate and tetrabutyl orthotitanate may suitably be used.
The boron-containing compound which is usable in the first step is not particularly limited. Preferred specific examples thereof may include boric acid, which can also be used in the form of a borate such as sodium borate.
The silicon-containing compound which is usable in the first step is not particularly limited. Specific examples thereof may include silicic acid, silicic acid salt, silicon oxide, silicon halide, fumed silicas, tetraalkyl orthosilicates and colloidal silica. In any of these cases, a silicon-containing compound having a high purity is preferred. More specifically, the silicon-containing compound may preferably have an alkali metal content such that the total moles of the alkali metal components is smaller than the moles of titanium, preferably {fraction (1/10)} times or less the moles of titanium, more preferably {fraction (1/100)} times or less the moles of titanium. Among these, in the case of colloidal silica, one having a smaller alkali content is preferred.
The ratio between titanium and silicon in the mixture to be used in the first step may preferably be 0.001 to 0.3:1 (titanium:silicon), more preferably 0.005 to 0.2:1 (titanium:silicon), particularly preferably 0.01 to 0.2:1 (titanium:silicon), in terms of the molar ratio therebetween.
The ratio between boron and silicon in the mixture to be used in the first step may preferably be 0.3 to 10:1 (boron:silicon), more preferably 0.5 to 5:1 (boron:silicon), particularly preferably 1 to 2:1 (boron:silicon), in terms of the molar ratio therebetween.
The ratio between water and silicon in the mixture to be used in the first step may preferably be 5 to 200:1 (water:silicon), more preferably 15 to 50:1 (water:silicon), in terms of the molar ratio therebetween.
The ratio between the template compound and silicon in the mixture to be used in the first step may preferably be 0.1 to 5:1 (template compound:silicon), more preferably 0.3 to 3:1 (template compound:silicon), particularly preferably 0.5 to 2:1 (template compound:silicon), in terms of the molar ratio therebetween.
These ratios of the mixture to be used in the first step are not particularly limited. However, in view of efficient provision of a high-activity crystalline MWW-type titanosilicate catalyst for providing an oxidized compound, each of the above-mentioned ranges is preferred. An element other than the elements described above can also be present together in the mixture to be used in the first step. However, if an alkali metal or an alkaline earth metal is present in a somewhat large amount, titanium may be prevented from entering into the framework. Therefore, the amount of an alkali metal or an alkaline earth metal may preferably be smaller. More specifically, for example, the total moles of an alkali metal and an alkaline earth metal may preferably be smaller than the moles of titanium. The total moles of an alkali metal and an alkaline earth metal may preferably be {fraction (1/10)} times or less the moles of titanium, more preferably {fraction (1/100)} times or less the moles of titanium.
The heating temperature to be used in the first step is not particularly limited. However, in the case of synthesizing a precursor, the heating may preferably be performed under hydrothermal reaction conditions. The term xe2x80x9chydrothermal reactionxe2x80x9d as used herein means, as described in Hyojun Kagaku Yogo Jiten (Standard Chemical Glossary), Item xe2x80x9cHydrothermal Reactionxe2x80x9d, edited by the Chemical Society of Japan, published by Maruzen (Mar. 30, 1991), a synthesis or a modification reaction of a substance to be performed in the presence of water at high temperature, particularly to be performed in the presence of water at high temperature and high pressure. A synthesis reaction utilizing the hydrothermal reaction is called xe2x80x9chydrothermal synthesisxe2x80x9d. Therefore, in the first step, the heating may preferably be performed under hydrothermal synthesis conditions such that a mixture comprising a template compound, a titanium-containing compound, a boron-containing compound, a silicon-containing compound and water is charged into a closed container such as autoclave and is pressurized under heating. The heating temperature may preferably be in the range of from 110 to 200xc2x0 C., more preferably from 120 to 190xc2x0 C.
If the temperature in the hydrothermal synthesis is below this range, the intended product may not be obtained, or even if obtained, the heating may take a long period of time, and such a procedure is not suitable for a practical purpose. On the other hand, if the temperature exceeds this range, the yield of the intended product is disadvantageously decreased in the oxidation reaction using the resultant catalyst which is finally been obtained in this manner.
The hydrothermal synthesis may usually be performed for 2 hours to 30 days, preferably for 3 hours to 10 days. If the hydrothermal synthesis time is less than this range, the crystallization can be insufficient so that a high-performance catalyst may not be obtained. On the other hand, even if the hydrothermal synthesis is performed for a time period exceeding this range, the resultant catalytic activity is not substantially enhanced. In this case, an adverse effect such as conversion of the materials into another phase or an increase in the particle size can be caused disadvantageously.
Next, the second step is described below. The second step is a step of calcining the precursor obtained in the first step, to thereby obtain a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound.
The method of calcining the precursor is not particularly limited and may be performed under known conditions in the usual calcination of a catalyst. The calcination may be performed in the closed system or in the flow system, and if desired, the calcination may be performed in an inert gas stream, such as nitrogen gas stream. The calcination temperature may preferably be in the range of from 200 to 700xc2x0 C., more preferably from 300 to 650xc2x0 C., particularly preferably from 400 to 600xc2x0 C. If the calcination temperature is less than 200xc2x0 C., the template compound may not be satisfactorily removed. On the other hand, if the calcination temperature exceeds 700xc2x0 C., the MWW-type crystal structure may be destroyed, and as a result, this destruction may adversely affect the resultant catalytic performance.
The process for producing a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound according to the present invention in the third aspect is described in detail below. The process for producing a catalyst according to the present invention in the third aspect is a process of converting a titanosilicate in an amorphous state into a precursor having a lamella phase called MCM-22(P) by using piperidine or hexamethyleneimine as a template, and using boron (boric acid) as a structure supporting agent (first step); and then calcining the precursor (second step), to thereby obtain a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound.
There is described a more specific embodiment of the process for producing a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound. For example, an aqueous solution of piperidine or hexamethyleneimine (template) is divided into two portions, tetraalkyl orthotitanate is added to one of the two portions and dissolved therein, a boron compound is added to the other of the two portions and dissolved therein, and silica is further added to each of the two portions, and then the resultant mixture are stirred, to prepare two kinds of homogenous gels containing titanium or boron.
These two kinds of gels are mixed with each other and thoroughly stirred, and thereafter the mixture is transferred to a closed container such as autoclave and subjected to a hydrothermal synthesis. The thus obtained solid product is separated from the mother liquor by filtration or the like, thoroughly washed with water and then dried. By calcining the thus obtained precursor, a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound can be obtained.
The catalyst which is obtainable by the production process according to the present invention in the third aspect may be used as a catalyst for an oxidation reaction as it is. The boron which has been introduced inside or outside the framework present in the titanosilicate obtained by this production process, or the anatase phase which has resulted from the condensation of titanium itself which does not participate in an oxidation reaction may be removed at least partially by contacting the catalyst with an acid. By the contact of the catalyst with the acid, the thus obtained crystalline MWW-type titanosilicate catalyst for providing an oxidized compound can have a higher performance.
A certain effect may be obtained, when the catalyst is contacted with an acid before or after the calcination, or both before and after the calcination in the process for producing a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound. However, a particularly enhanced effect can be obtained, when the catalyst in the precursor state is contacted with an acid before the calcination. In the latter case, the by-product anatase phase due to the calcination can be strongly suppressed.
The xe2x80x9ccontact with an acidxe2x80x9d as used herein specifically means an operation such that a solution containing an acid or an acid itself is contacted with the precursor which has been obtained after the first step, or with the titanosilicate which has been obtained after the second step. The contacting method is not particularly limited. The contacting method may be a method of spraying or applying an acid or an acid solution to the precursor or titanosilicate, or a method of dipping the precursor or titanosilicate in an acid or an acid solution. The method of dipping the precursor or titanosilicate in an acid or an acid solution is simple and easy, and therefore this method is preferred.
The acid to be used for the above-mentioned acid contact may be an inorganic acid, an organic acid or a salt of these acids. Specific examples of preferred inorganic acids may include hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid. Specific examples of preferred organic acids may include formic acid, acetic acid, propionic acid and tartaric acid. Examples of the salt of these acids may include sodium salt, potassium salt, calcium salt, magnesium salt and ammonium salt of these acids.
The contact with an acid may be performed either before or after the calcination as described above, but may preferably be performed before the calcination so as to attain an enhanced effect. A solid substance such as precursor is dipped in an acid solution in an amount of approximately from 5 to 100 ml per one gram of the solid substance, and kept therein for a predetermined time. Thereafter, the solid is recovered from the acid solution by filtration or the like, and then thoroughly washed with a solvent. Stirring is not always necessary but may be performed.
In the case of using the acid in the form of a solution, the solvent is not particularly limited. Specific examples thereof may include water, alcohols, ethers, esters and ketones. Among these, water is preferred.
The acid concentration is not particularly limited but may suitably be on the order of 0.1 to 10 mol/l. The temperature may be in the range of from 0 to 200xc2x0 C., but may preferably be from 50 to 180xc2x0 C., more preferably from 60 to 150xc2x0 C. The treatment time may be from 0.1 hour to 3 day, but may suitably be from 2 hours to 1 day.
The present invention in a fourth aspect is described below. The present invention in the fourth aspect is a process for producing an oxidized compound comprising: performing an oxidation reaction of a compound having a carbon-carbon double bond and at least one of other functional group wherein the carbon-carbon double bond of the compound is oxidized by using a peroxide as an oxidizing agent in the presence of the crystalline MWW-type titanosilicate catalyst for providing an oxidized compound according to the present invention in the first or second aspect. According to the production process for an oxidized compound according to the present invention in the fourth aspect, the oxidation reaction of a carbon-carbon double bond only can be selectively performed substantially without affecting other functional groups of the compound having a carbon-carbon double bond and at least one of other functional group. Needless to say, other functional groups may be simultaneously reacted, to thereby obtain an entirely different product. Such a case, of course, may be included in the scope of the present invention in the fourth aspect.
Specific examples of the peroxide which is usable in the present invention in the fourth aspect may include hydrogen peroxide and organic peroxides. Examples of the organic peroxide may include tert-butyl hydroperoxide, tert-amyl hydroperoxide, cumene hydroperoxide, ethylbenzene hydroperoxide, cyclohexyl hydroperoxide, methylcyclohexyl hydroperoxide, tetralin (i.e., tetrahydronaphtalene) hydroperoxide, isobutylbenzene hydroperoxide, ethylnaphthalene hydroperoxide and peracetic acid. However, the peroxides usable in the present invention are not limited to these specific compounds. These peroxides may also be used in combination of two or more species thereof.
The peroxide to be used for such a purpose may particularly preferably be hydrogen peroxide. An aqueous hydrogen peroxide solution having any of various concentrations may be used. Examples of such concentrations may include, e.g., 30 mass %, 60 mass %, 90 mass % or the like. The amount of peroxide to be added to the reactant is not particularly limited, and the amount may be equivalent or more to the carbon-carbon double bond of the compound having a carbon-carbon double bond and at least one of other functional group, which is a raw material to be subjected to an oxidation reaction, or the amount may be equivalent or less, depending on the conditions.
The compound having a carbon-carbon double bond and at least one of other functional group for use in the process for producing an oxidized compound according to the present invention in the fourth aspect is not particularly limited, and may be any compound as long as it has a carbon-carbon double bond and at least one other functional group within one molecule thereof. In this case, a compound containing two or more carbon-carbon double bonds, of course, may be included within the definition of the above xe2x80x9ccompound having a carbon-carbon double bond and at least one of other functional groupxe2x80x9d.
Specific examples of the other functional group may include an alkenyl group, an alkynyl group, an aryl group, an arene group, an alcohol group, a phenol group, an ether group, an epoxide group, a halogen group, an aldehyde group, a ketone group, a carbonyl group, an ester group, an amide group, a cyanate group, an isocyanate group, a thiocyanate group, an amine group, a diazo group, a nitro group, a nitrile group, a nitroso group, a sulfide group, a sulfoxide group, a sulfone group, a thiol group, an orthoester group, a urea group and imine group. However, the xe2x80x9cother functional groupxe2x80x9d usable in the present invention is not limited to these specific compounds. Two or more of the same functional group may be contained in one molecule, and/or two or more kinds of functional groups may be contained in one molecule.
More specific examples of the compound having a carbon-carbon double bond and at least one other functional group may include allyl ethers, compounds having from 3 to 10 carbon atoms, ethers of polyhydric alcohol, and carboxylic acid esters. Of course, these compounds may also be used in combination of two or more species thereof.
More specifically, examples of the allyl ethers may include allyl methyl ether, allyl ethyl ether, allyl propyl ether, allyl butyl ether, allyl vinyl ether and diallyl ether.
Examples of the compounds having from 3 to 10 carbon atoms may include allyl alcohol, allyl bromide, allyl chloride, acrolein, methacrolein and acrylic acid.
Examples of the ethers of polyhydric alcohol may include ethylene glycol monoalkenyl ether, ethylene glycol dialkenyl ether, 1,2-propanediol monoalkenyl ether, 1,2-propanediol dialkenyl ether, 1,3-propanediol monoalkenyl ether, 1,3-propanediol dialkenyl ether, 1,2-butanediol monoalkenyl ether, 1,2-butanediol dialkenyl ether, 1,3-butanediol monoalkenyl ether, 1,3-butanediol dialkenyl ether, 1,4-butanediol monoalkenyl ether, 1,4-butanediol dialkenyl ether, and pentaerythritol monoalkenyl ether, pentaerythritol dialkenyl ether, pentaerythritol trialkenyl ether and pentaerythritol tetraalkenyl ether, trimethylolpropane monoalkenyl ether, trimethylolpropane dialkenyl ether, and trimethylolpropane trialkenyl ether.
Examples of the carboxyllic acid esters may include allyl formate, allyl acetate, allyl tartrate, allyl propionate and allyl methacrylate.
Examples of particularly preferred combination may include a combination such that the compound having a carbon-carbon double bond and at least one of other functional group is diallyl ether, allyl acetate, allyl methacrylate or allyl alcohol and the oxidizing agent is hydrogen peroxide.
The amount of the crystalline MWW-type titanosilicate catalyst for providing an oxidized compound used in the process for producing an oxidized compound according to the present invention in the fourth aspect is not particularly limited. The preferred range thereof may vary depending on the kind of oxidation reaction, the reaction temperature, the reactivity and temperature of the substrate or reactant, the concentration of peroxide, the kind and concentration of solvent, and the reaction form or type (e.g., batch system, continuous system). In a case where the catalyst is used in a slurry system, the amount of the catalyst may usually be in the range of from 0.1 to 20 mass %, more preferably from 0.5 to 10 mass %, in terms of the concentration of the catalyst in the reactant mixture. In the case of a fixed-bed flow reaction system, the apparent amount of the catalyst may preferably be larger than the above-mentioned range.
The shape or form of the crystalline MWW-type titanosilicate catalyst for providing an oxidized compound is not particularly limited. The form may be a powder, microspheres, pellets or extrusion-molded articles, or the catalyst may also be in a form such that it is supported on a support or carrier. In the molding of the catalyst, a binder may be used. The binder or support for such a purpose may preferably be a substance which is substantially non-acidic or weakly acidic, and which does not accelerate the decomposition reaction of the peroxide or the decomposition reaction of the intended oxidized compound.
The oxidation reaction in the process for producing an oxidized compound according to the present invention in the fourth aspect may be performed without using a solvent or in the presence of an appropriate solvent. Examples of the appropriate solvent may include alcohols, ketones, nitrites and water. Specific examples of alcohols may include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, amyl alcohol, ethylene glycol, propylene glycol and 1,2-butanediol. Specific examples of ketones may include acetone, methyl ethyl ketone and diethyl ketone. Specific examples of nitrites may include acetonitrile, propionitrile and benzonitrile. These may be used singly or as a mixture thereof. Among these solvents, preferred are acetone, acetonitrile and water, and more preferred is acetonitrile.
In the process for producing an oxidized compound according to the present invention in the fourth aspect, the reaction temperature at the oxidation reaction, which is not particularly limited, may preferably be from 0 to 150xc2x0 C., more preferably from 10 to 100xc2x0 C. If the reaction temperature is less than 0xc2x0 C., the reaction rate is low and this temperature is not suitable for practical purposes. On the other hand, if the temperature exceeds 150xc2x0 C., a decomposition reaction of the peroxide may seriously proceed and, further, a decomposition reaction of the intended product may disadvantageously be accelerated.
The oxidation reaction is generally an exothermic reaction, and therefore, the heat of reaction may preferably be removed by a suitable method so as to control the reaction temperature to a constant range. The reaction pressure is not particularly limited.
The oxidation reaction in the process for producing an oxidized compound according to the present invention in the fourth aspect may be performed by any method in a batch system, a continuous system or a semi-continuous system, e.g., by using a suitable reactor or reaction apparatus such as fixed bed reactor, fludized-bed reactor, moving-bed reactor, tank reactor, stirring slurry-type reactor, continuous stirred tank reactor (CSTR). With respect to the mixture containing a crystalline MWW-type titanosilicate catalyst for providing an oxidized compound, a compound having a carbon-carbon double bond and at least one other functional group and a peroxide, these components constituting the mixture may be mixed partially or all at once or may be mixed in sequence or in order. It is also possible to mix the two species selected from the three species of these components (i.e., the catalyst, the compound having a carbon-carbon double bond and at least one of other functional group, and the peroxide), and then mix the remaining one species of these components into such a mixture.
In this reaction, the intended oxidized compound (reaction product) may be separated by a separation/purification method used in an ordinary purification procedure. More specifically, for example, when the reaction is performed in a batch system, when the amount of the oxidized compound which has been produced reaches a value in the desired region, the oxidized compound may be separated and recovered from the reaction mixture by using any known method such as fractional distillation, extract distillation or liquid-liquid extraction.
In the case of a slurry-type reactor, the crystalline MWW-type titanosilicate catalyst for providing an oxidized compound can be recovered by a suitable method such as filtration or centrifugation, and the thus recovered catalyst can be reused as a catalyst for oxidation reaction.
In the case of a fixed bed-type reactor, the crystalline MWW-type titanosilicate catalyst for providing an oxidized compound can be easily separated from the product (oxidized compound), the solvent, the unreacted compound having a carbon-carbon double bond and at least one of other functional group and the peroxide, while the catalyst remains being held in the reactor.
In the process for producing an oxidized compound according to the present invention in the fourth aspect, at least one of the recovered crystalline MWW-type titanosilicate catalyst for providing an oxidized compound, the unreacted compound having a carbon-carbon double bond and at least one of other functional group and the peroxide can be reused, after purification by an appropriate method or without purification thereof.
In the present invention in the fourth aspect, the recovered crystalline MWW-type titanosilicate catalyst for providing an oxidized compound generally has a tendency such that the activity thereof is decreased each time it is used repeatedly, and the catalyst after the repeated use cannot exhibit its initial activity. In such a case, the recovered catalyst may be regenerated or reproduced. The recovered catalyst may be regenerated by a conventionally known method. More specifically, the catalyst may be regenerated so that it has an initial activity, for example, by calcining the catalyst in air at a temperature of 100 to 600xc2x0 C.